The present invention relates to electromechanical thrust reverser actuation systems and, more particularly, to a system architecture for interfacing an electromechanical thrust reverser actuation system to an engine control system having a plurality of redundant channels.
When jet-powered aircraft land, the landing gear brakes and imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to slow the aircraft down in the required amount of distance. Thus, jet engines on most aircraft include thrust reversers to enhance the stopping power of the aircraft. When deployed, thrust reversers redirect the rearward thrust of the jet engine to a forward direction, thus decelerating the aircraft. Because the jet thrust is directed forward, the aircraft will slow down upon landing.
Various thrust reverser designs are known, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with turbofan jet engines fall into three general categories: (1) cascade-type thrust reversers; (2) target-type thrust reversers; and (3) pivot door thrust reversers. As will be discussed more fully below, each of these designs employs a different type of xe2x80x9cmoveable thrust reverser component,xe2x80x9d as that term is defined below.
Cascade-type thrust reversers are normally used on high-bypass ratio jet engines. This type of thrust reverser is located at the engine""s midsection and, when deployed, exposes and redirects air flow through a plurality of cascade vanes positioned on the outside of the engine. The moveable thrust reverser component in this design may include several translating sleeves or cowls (xe2x80x9ctranscowlsxe2x80x9d) that are deployed to expose the cascade vanes. Target-type reversers, also referred to as clamshell reversers, are typically used with low-bypass ratio jet engines. Target-type thrust reversers use two doors as the moveable thrust reverser component to block the entire jet thrust coming from the rear of the engine. These doors are mounted on the aft portion of the engine and form the rear part of the engine nacelle. Pivot door thrust reversers may utilize four doors on the engine nacelle as the moveable thrust reverser component. In the deployed position, these doors extend outwardly from the nacelle to redirect the jet thrust.
The primary use of thrust reversers is, as noted above, to enhance the stopping power of the aircraft, thereby shortening the stopping distance during landing. Hence, thrust reversers are primarily deployed during the landing process. More specifically, once the aircraft has touched down on the runway, the thrust reversers are deployed to assist in slowing the aircraft. Thereafter, when the thrust reversers are no longer needed, they are returned to their original, stowed position. In the stowed position, one or more stow seals prevent air from flowing through the transcowls or doors, depending on the thrust reverser design. Moreover, stow locks are engaged to prevent unintended deployment of the thrust reversers.
The movement of the thrust reverser moveable components in each of the above-described designs is most often accomplished via a hydraulic system. Such systems include hydraulic controllers and lines coupled to the aircraft""s hydraulic system, hydraulic actuators connected to the moveable components, and hydraulically controlled locking mechanisms. More recently, however, thrust reverser actuation is being controlled by electromechanical systems. These systems include one or more electronic controllers that control the operation of electromechanical actuators that are connected to the moveable components, and one or more electrically operated locking mechanisms. One such electromechanical thrust reverser system is shown in U.S. Pat. No. 5,960,626 (xe2x80x9cthe ""626 patentxe2x80x9d).
An electromechanical thrust reverser actuation system includes safety critical control and indication functions, such as control and position indication of the thrust reverser locking mechanisms and position indication of the thrust reverser moveable components. This is significant since aviation systems that include control and indication functions that are classified as essential or critical to flight safety are required to meet certain design criteria. These design criteria include both redundancy and separation of the critical control and indication functions, which are implemented in one of two ways. The first is through the use of a symmetric system architecture and the second is through the use of a primary/alternate system architecture. With a symmetric system architecture, all control and indication functions are implemented in functionally similar, but electrically isolated, channels. With a primary/alternate system architecture, all control and indication functions, including both essential and non-essential functions, are included in the primary channel, and all essential control and indication functions are included in an alternate, electrically isolated (and perhaps physically isolated) channel.
Hence, in order for an electromechanical thrust reverser actuation system to be commercially viable, it should be designed to meet the above-noted redundancy and separation requirements. Moreover, it should also be designed to interface directly to the aircraft engine control system, such as the Fully Automated Digital Engine Control (xe2x80x9cFADEC) system, which is also designed to meet the redundancy and separation requirements. The electromechanical thrust reverser system disclosed in the ""626 patent does not address the use of multiple channels, but instead shows a system being coupled to a single FADEC channel. The failure of this single FADEC channel could result in loss of safety critical thrust reverser control and/or indication functions.
Hence, there is a need for an electromechanical thrust reverser system architecture that meets redundancy and separation requirements and interfaces with an engine control system that is also designed to meet these requirements.
In addition, a very cost effective and lightweight electromechanical thrust reverser actuation system design uses the primary/alternate system architecture. However, many aircraft designs use a symmetric architecture in their engine control systems. Hence, there is additionally a need for a primary/alternate electromechanical thrust reverser actuation system architecture that interfaces with a symmetric channel engine control architecture.
The present invention provides a system architecture for interfacing an electromechanical thrust reverser actuation system that meets redundancy and isolation requirements to an aircraft engine control system that is also designed to meet redundancy and isolation requirements.
In an aspect of the present invention, and by way of example only, an electromechanical thrust reverser actuation system for interfacing to a jet engine control system having at least first and second engine control system channels, a thrust reverser controller, and at least one motor. The thrust reverser controller has at least two electrically isolated thrust reverser controller channels, each of which is coupled to receive command signals from one of the engine control channels and at least one of the thrust reverser controller channels and is operable, in response to the commands, to transmit thrust reverser motor actuation control signals. The motor is coupled to receive the thrust reverser motor actuation control signals from one of the thrust reverser control channels and is operable, in response thereto, to move a thrust reverser between a stowed position and a deployed position.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.